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Publication 1762-UM002A-EN-P - July 2002

D-4

Using Thermocouple Junctions

To prevent violation of channel-to-channel isolation:

•

For multiple exposed junction thermocouples, do not allow the
measuring junctions to make direct contact with electrically
conductive process material.

•

Preferably use a single exposed junction thermocouple with
multiple ungrounded junction thermocouples.

•

Consider using all ungrounded junction thermocouples instead
of the exposed junction type.

Содержание MicroLogix 1200

Страница 1: ...MicroLogix 1200 Thermocouple mV Input Module Catalog Number 1762 IT4 User Manual AB Parts...

Страница 2: ...the Application Installation and Maintenance of Solid State Control available from your local Allen Bradley office describes some important differences between solid state equipment and electromechan...

Страница 3: ...anges 1 1 Data Formats 1 2 Filter Frequencies 1 2 Hardware Features 1 2 General Diagnostic Features 1 4 System Overview 1 4 System Operation 1 4 Module Operation 1 5 Module Field Calibration 1 6 Chapt...

Страница 4: ...Configuring Channels 3 4 Configuration Data File 3 4 Channel Configuration 3 4 Enabling or Disabling a Channel Bit 15 3 6 Selecting Data Formats Bits 14 through 12 3 6 Selecting Input Type Bits 11 thr...

Страница 5: ...cations A 2 Repeatability at 25 C 77 F A 3 Accuracy A 4 Accuracy Versus Thermocouple Temperature and Filter Frequency A 5 Appendix B Two s Complement Binary Numbers Positive Decimal Values B 1 Negativ...

Страница 6: ...e Configuration Using MicroLogix 1200 and RSLogix 500 Module Addressing E 1 1762 IT4 Configuration File E 2 Configuration Using RSLogix 500 Version 5 50 or Higher E 2 Generic Extra Data Configuration...

Страница 7: ...rganized this manual to explain in a task by task manner how to install configure program operate and troubleshoot a control system using the 1762 IT4 Manual Contents If you want See An overview of th...

Страница 8: ...ed throughout this manual Bulleted lists like this one provide information not procedural steps Numbered lists provide sequential steps or hierarchical information Italic type is used for emphasis For...

Страница 9: ...duct technical training warranty support support service agreement Technical Product Assistance If you need to contact Rockwell Automation for technical assistance please review the information in Cha...

Страница 10: ...Publication 1762 UM002A EN P July 2002 Preface 4...

Страница 11: ...gurable via software for a specific input device data format and filter frequency and provides open circuit over range and under range detection and indication Thermocouple mV Inputs and Ranges The ta...

Страница 12: ...r is programmable allowing you to select from six different filter frequencies for each channel 10 Hz 50 Hz 60 Hz 250 Hz 500 Hz 1000 Hz Hardware Features Channels are wired as differential inputs A co...

Страница 13: ...tures 1a 1b 5 2 3 9 4 6 7 1a 1b 2 6 8 Item Description 1a upper panel mounting tab 1b lower panel mounting tab 2 power diagnostic LED 3 module door with terminal identification label 5 bus connector c...

Страница 14: ...complete the module waits for valid channel configuration data If an invalid configuration is detected the module generates a configuration error Once a channel is properly configured and enabled it...

Страница 15: ...s from a thermocouple or millivolt analog input device depending upon how you configured the channel When configured for thermocouple input types the module converts the analog input voltages into col...

Страница 16: ...ule An internal high precision low drift voltage and system ground reference is used for this purpose The input module performs autocalibration when a channel is initially enabled In addition you can...

Страница 17: ...ion within the European Union and EEA regions It has been designed and tested to meet the following directives EMC Directive The 1762 IT4 module is tested to meet Council Directive 89 336 EEC Electrom...

Страница 18: ...the module is shown in the table below General Considerations 1762 I O is suitable for use in an industrial environment when installed in accordance with these instructions Specifically this equipmen...

Страница 19: ...o be non hazardous Do not connect or disconnect components unless power has been switched off or the area is known to be non hazardous This product must be installed within an enclosure All wiring mus...

Страница 20: ...ch as hard contact switches relays and AC motor drives away from modules which generate significant radiated heat Refer to the module s heat dissipation specification In addition route shielded twiste...

Страница 21: ...h will momentarily open and lock into place ATTENTION Do not remove protective debris strip until after the module and all other equipment near the module is mounted and wiring is complete Once wiring...

Страница 22: ...panhead screws may also be used but a washer may be needed to ensure a good ground contact Mounting screws are required on every module TIP For environments with extreme vibration and shock concerns...

Страница 23: ...ls are isolated from one another by 10 Vdc maximum If multiple power supplies are used with analog millivolt inputs the power supply commons must be connected TIP Use the pull loop on the connector to...

Страница 24: ...product is intended to be mounted to a well grounded mounting surface such as a metal panel Additional grounding connections from the module s mounting tabs or DIN rail if used are not required unless...

Страница 25: ...allow at least 15 2 cm 6 in of separation for every 120V of power Routing field wiring in a grounded conduit can reduce electrical noise If field wiring must cross ac or power cables ensure that they...

Страница 26: ...commended torque when tightening terminal screws is 0 904 Nm 8 in lbs 3 After wiring is complete remove the debris shield ATTENTION Be careful when stripping wires Wire fragments that fall into a modu...

Страница 27: ...ill be visible when the module door is closed Wiring the Module After the module is properly installed follow the wiring procedure on page 2 12 using the proper thermocouple extension cable or Belden...

Страница 28: ...type of sensor you are using See Grounding on page 2 8 4 At the other end of the cable cut the drain wire and foil shield back to the cable and apply shrink wrap 5 Connect the signal wires to the term...

Страница 29: ...ithin 10V dc grounded thermocouple grounded thermocouple ungrounded thermocouple CJC sensor TIP When using an ungrounded thermocouple the shield must be connected to ground at the module end IMPORTANT...

Страница 30: ...ing is taken The A D converter uses these numbers to compensate for system offset zero and gain span errors Autocalibration of a channel occurs whenever a channel is enabled You can also program your...

Страница 31: ...and status bits input image and five configuration words Accessing Input Image File Data The input image file represents data words and status words Input words 0 through 3 hold the input data that r...

Страница 32: ...on is described below Input Data Not Valid Condition The general status bits S0 to S3 also indicate whether or not the input data for a particular channel 0 through 3 is being properly converted valid...

Страница 33: ...cuit operation Over Range Flag Bits O0 to O4 Over range bits for channels 0 through 3 and the CJC sensor are contained in word 5 even numbered bits They apply to all input types When set 1 the over ra...

Страница 34: ...annel Configuration Each channel configuration word consists of bit fields the settings of which determine how the channel operates See the table below and the descriptions that follow for valid confi...

Страница 35: ...uple T 0 0 1 0 512 Thermocouple E 0 0 1 1 768 Thermocouple R 0 1 0 0 1024 Thermocouple S 0 1 0 1 1280 Thermocouple B 0 1 1 0 1536 Thermocouple N 0 1 1 1 1792 Thermocouple C 1 0 0 0 2048 50 to 50 mV 1...

Страница 36: ...210 to 1200 346 to 2192 0 to 16383 32767 to 32767 0 to 10000 K 2700 to 13700 4540 to 24980 270 to 1370 454 to 2498 0 to 16383 32767 to 32767 0 to 10000 T 2700 to 4000 4540 to 7520 270 to 400 454 to 7...

Страница 37: ...data format for a thermocouple or millivolt input the module scales the thermocouple or millivolt input data to the actual engineering values for the selected millivolt input or thermocouple type It...

Страница 38: ...r input range To obtain the value the module scales the input signal range to a 0 to 16383 range which is standard to the PID algorithm for the MicroLogix 1200 and other Allen Bradley controllers e g...

Страница 39: ...n it detects an open circuit The open circuit options are explained in the table on page 3 10 IMPORTANT If you are using engineering units x 1 data format and degrees Fahrenheit temperature units ther...

Страница 40: ...resolution but also increases channel update time A higher filter frequency provides lower noise rejection but decreases the channel update time and effective resolution When selecting a filter freque...

Страница 41: ...gnal to reach 100 of its expected final value given a full scale step change in the input signal This means that if an input signal changes faster than the channel step response a portion of that sign...

Страница 42: ...g table shows cut off frequencies for the supported filters All input frequency components at or below the cut off frequency are passed by the digital filter with less than 3 dB of attenuation All fre...

Страница 43: ...20 0 40 60 80 100 120 140 160 180 200 20 0 40 60 80 100 120 140 160 180 200 20 0 40 60 80 100 120 140 160 180 200 20 3 dB 1300 0 1150 750 500 250 65 5 Hz 900 3 dB 3000 0 2500 1500 1000 500 131 Hz 200...

Страница 44: ...annels Setting this bit to 1 disables cyclic calibration You can program the calibration cycle to occur whenever you desire for systems that allow modifications to the state of this bit via the ladder...

Страница 45: ...Filter Selection for Type B Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 5 1 0 1 5 2 0 2 5 200 400 600 800 1000 1200 1400 1600 1800 2000 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5...

Страница 46: ...put Filter Selection for Type B Thermocouples Using 250 500 and 1k Hz Filters 0 50 100 150 200 250 300 350 200 400 600 800 1000 1200 1400 1600 1800 2000 250 Hz 500 Hz 1000Hz 0 100 200 300 400 500 600...

Страница 47: ...lter Selection for Type C Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 400 800 1200 1600 2000 2400 10 Hz 50 Hz 60 Hz 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 1 6 0 500 1000...

Страница 48: ...t Filter Selection for Type C Thermocouples Using 250 500 and 1k Hz Filters 0 20 40 60 80 100 120 140 160 180 0 400 800 1200 1600 2000 2400 250 Hz 500 Hz 1000 Hz 0 50 100 150 200 250 300 350 0 500 100...

Страница 49: ...s Input Filter Selection for Type E Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 5 1 0 1 5 2 0 2 5 3 0 400 200 0 200 400 600 800 1000 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0...

Страница 50: ...lution Versus Input Filter Selection for Type E Thermocouples Using 250 500 and 1k Hz Filters 0 20 40 60 80 100 400 200 0 200 400 600 800 1000 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 160 500 0...

Страница 51: ...n Versus Input Filter Selection for Type J Thermocouples Using 10 50 and 60 Hz Filters 0 0 1 0 2 0 3 0 4 400 200 0 200 400 600 800 1000 1200 10 Hz 50 Hz 60 Hz 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 400 0 400 8...

Страница 52: ...ution Versus Input Filter Selection for Type J Thermocouples Using 250 500 and 1k Hz Filters 0 10 20 30 40 50 60 400 200 0 200 400 600 800 1000 1200 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 400 0 40...

Страница 53: ...Selection for Type K Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 400 200 0 200 400 600 800 1000 1200 10 Hz 50 Hz 60 Hz 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8...

Страница 54: ...s Input Filter Selection for Type K Thermocouples Using 250 500 and 1k Hz Filters 0 20 40 60 80 100 120 400 200 0 200 400 600 800 1000 1200 250Hz 500Hz 1000 Hz 0 20 40 60 80 100 120 140 160 180 200 22...

Страница 55: ...ut Filter Selection for Type N Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 400 200 0 200 400 600 800 1000 1200 1400 10 Hz 50 Hz 60 Hz 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1...

Страница 56: ...s Input Filter Selection for Type N Thermocouples Using 250 500 and 1k Hz Filters 0 20 40 60 80 100 120 400 200 0 200 400 600 800 1000 1200 1400 250Hz 500Hz 1000 Hz 0 20 40 60 80 100 120 140 160 180 2...

Страница 57: ...nput Filter Selection for Type R Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 0 200 400 600 800 1000 1200 1400 1600 1800 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 0 500...

Страница 58: ...Input Filter Selection for Type R Thermocouples Using 250 500 and 1k Hz Filters 0 50 100 150 200 250 0 200 400 600 800 1000 1200 1400 1600 1800 250 Hz 500 Hz 1000Hz 0 50 100 150 200 250 300 350 400 0...

Страница 59: ...nput Filter Selection for Type S Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 0 200 400 600 800 1000 1200 1400 1600 1800 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 0 500...

Страница 60: ...Input Filter Selection for Type S Thermocouples Using 250 500 and 1k Hz Filters 0 50 100 150 200 250 0 200 400 600 800 1000 1200 1400 1600 1800 250Hz 500Hz 1000Hz 0 50 100 150 200 250 300 350 400 0 5...

Страница 61: ...s Input Filter Selection for Type T Thermocouples Using 10 50 and 60 Hz Filters 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 300 200 100 0 100 200 300 400 10 Hz 50 Hz 60 Hz 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 600...

Страница 62: ...rsus Input Filter Selection for Type T Thermocouples Using 250 500 and 1k Hz Filters 0 20 40 60 80 100 120 300 200 100 0 100 200 300 400 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 160 180 200 220...

Страница 63: ...enabled channels in a continuous loop as shown below Table 3 4 Effective Resolution vs Input Filter Selection for Millivolt Inputs Filter Frequency 50mV 100mV 10 Hz 6 V 6 V 50 Hz 9 V 12 V 60 Hz 9 V 12...

Страница 64: ...gram to Run for all configured channels or if any online 1 configuration change is made to a channel In addition you can configure the module to perform autocalibration every 5 minutes during normal o...

Страница 65: ...low for channel and CJC sensor ADC self calibration times as well as channel offset calibration times Calculating Module Update Time To determine the module update time add the individual channel upda...

Страница 66: ...le Update Time without an Autocalibration Cycle Ch 0 Update Time Ch 1 Update Time Ch 2 Update Time CJC Update Time uses lowest thermocouple filter selected 53 ms 53 ms 53 ms 53 ms 212 ms Module Update...

Страница 67: ...ections as indicated in Table 3 5 Channel Update Time on page 3 34 The following is an example calculation of module startup time EXAMPLE 1 Two Channels Enabled for Different Inputs Channel 0 Input Ty...

Страница 68: ...Publication 1762 UM002A EN P July 2002 3 38 Module Data Status and Channel Configuration...

Страница 69: ...ely thinking about the safety of yourself and others as well as the condition of your equipment is of primary importance The following sections describe several safety concerns you should be aware of...

Страница 70: ...se devices must be wired in series so that when any one device opens the master control relay is de energized thereby removing power to the machine Never alter these circuits to defeat their function...

Страница 71: ...operly defined the module reports an error See pages 4 4 to 4 6 for a description of module errors Over or Under Range Detection Whenever the data received at the channel word is out of the defined op...

Страница 72: ...ystem When these types of errors occur the system typically leaves the run or program mode of operation until the error can be dealt with Critical module errors are indicated in Table 4 3 Extended Err...

Страница 73: ...onfiguration file to invalid or unsupported values the module generates a critical error Table 4 3 Extended Error Codes on page 4 6 lists the possible module specific configuration error codes defined...

Страница 74: ...00 0001 Invalid input type selected channel 0 X402 010 0 0000 0010 Invalid input type selected channel 1 X403 010 0 0000 0011 Invalid input type selected channel 2 X404 010 0 0000 0100 Invalid input t...

Страница 75: ...available when you call a clear statement of the problem including a description of what the system is actually doing Note the LED state also note data and configuration words for the module a list of...

Страница 76: ...Publication 1762 UM002A EN P July 2002 4 8 Diagnostics and Troubleshooting...

Страница 77: ...Hz 5G 0 030 in peak to peak Relay Operation 2G Shock Operating 30G 11 ms panel mounted 20G 11 ms DIN rail mounted Relay Operation 7 5G panel mounted 5G DIN rail mounted Non Operating 40G panel mounte...

Страница 78: ...of Filter Frequency on Noise Rejection on page 3 10 Rated Working Voltage 1 1 Rated working voltage is the maximum continuous voltage that can be applied at the input terminal including the input sign...

Страница 79: ...t reporting Vendor I D Code 1 Product Type Code 10 Product Code 64 1 Repeatability is the ability of the input module to register the same reading in successive measurements for the same input signal...

Страница 80: ...F 7 5 C 13 5 F 10 C 18 F 0 0378 C C 0 0378 F F Thermocouple E 210 C to 1000 C 346 F to 1832 F 0 5 C 0 9 F 0 8 C 1 5 F 0 0199 C C 0 0199 F F Thermocouple E 270 C to 210 C 454 F to 346 F 4 2 C 7 6 F 6 3...

Страница 81: ...e for each frequency The effect of errors in cold junction compensation is not included Figure A 1 Module Accuracy at 25 C 77 F Ambient for Type B Thermocouple Using 10 50 and 60 Hz Filter 0 0 0 5 1 0...

Страница 82: ...r Type B Thermocouple Using 250 500 and 1 kHz Filter 0 40 80 120 160 200 240 200 400 600 800 1000 1200 1400 1600 1800 2000 250 Hz 500 Hz 1000Hz 0 50 100 150 200 250 300 350 400 500 1000 1500 2000 2500...

Страница 83: ...e Using 10 50 and 60 Hz Filter 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 1 6 1 8 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 0 500 1000 1500 2000...

Страница 84: ...ype C Thermocouple Using 250 500 and 1 kHz Filter 0 10 20 30 40 50 60 70 80 90 100 0 400 800 1200 1600 2000 2400 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 160 180 0 500 1000 1500 2000 2500 3000 3...

Страница 85: ...bient for Type E Thermocouple Using 10 50 and 60 Hz Filter 0 0 1 0 2 0 3 0 4 0 5 0 400 200 0 200 400 600 800 1000 10 Hz 50 Hz 60 Hz 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 500 0 500 1000 1500 2000 10...

Страница 86: ...mbient for Type E Thermocouple Using 250 500 and 1 kHz Filter 0 10 20 30 40 50 60 70 400 200 0 200 400 600 800 1000 250 Hz 500 Hz 1000Hz 0 10 20 30 40 50 60 70 80 90 100 110 120 500 0 500 1000 1500 20...

Страница 87: ...nt for Type J Thermocouple Using 10 50 and 60 Hz Filter 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 400 200 0 200 400 600 800 1000 1200 10 Hz 50 Hz 60 Hz 0 0 0 2 0 4 0 6 0 8 1 0 1 2 400 0 400 800 1200 1600 2000 240...

Страница 88: ...Ambient for Type J Thermocouple Using 250 500 and 1 kHz Filter 0 5 10 15 20 25 30 35 40 400 200 0 200 400 600 800 1000 1200 250 Hz 500 Hz 1000Hz 0 10 20 30 40 50 60 70 400 0 400 800 1200 1600 2000 240...

Страница 89: ...K Thermocouple Using 10 50 and 60 Hz Filter 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 400 200 0 200 400 600 800 1000 1200 1400 10 Hz 50 Hz 60 Hz 0 0 2 0 4 0 6 0 8 0 10 0 12 0 14 0 16 0 500 0 500 1000 15...

Страница 90: ...for Type K Thermocouple Using 250 500 and 1 kHz Filter 0 10 20 30 40 50 60 70 80 90 100 400 200 0 200 400 600 800 1000 1200 1400 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 160 500 0 500 1000 1500...

Страница 91: ...t for Type N Thermocouple Using 10 50 and 60 Hz Filter 0 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 400 200 0 200 400 600 800 1000 1200 1400 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 500 0 500 1000 1500 2000 2500...

Страница 92: ...mbient for Type N Thermocouple Using 250 500 and 1 kHz Filter 0 10 20 30 40 50 60 70 400 200 0 200 400 600 800 1000 1200 1400 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 500 0 500 1000 1500 2000 25...

Страница 93: ...Type R Thermocouple Using 10 50 and 60 Hz Filter 0 0 0 5 1 0 1 5 2 0 2 5 0 200 400 600 800 1000 1200 1400 1600 1800 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 0 500 1000 1500 2000 2500...

Страница 94: ...ent for Type R Thermocouple Using 250 500 and 1 kHz Filter 0 20 40 60 80 100 120 140 0 200 400 600 800 1000 1200 1400 1600 1800 250 Hz 500 Hz 1000 Hz 0 50 100 150 200 250 0 500 1000 1500 2000 2500 300...

Страница 95: ...Type S Thermocouple Using 10 50 and 60 Hz Filter 0 0 0 5 1 0 1 5 2 0 2 5 0 200 400 600 800 1000 1200 1400 1600 1800 10 Hz 50 Hz 60 Hz 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 0 500 1000 1500 2000 2500...

Страница 96: ...ient for Type S Thermocouple Using 250 500 and 1 kHz Filter 0 20 40 60 80 100 120 140 0 200 400 600 800 1000 1200 1400 1600 1800 250 Hz 500 Hz 1000Hz 0 50 100 150 200 250 0 500 1000 1500 2000 2500 300...

Страница 97: ...5 C 77 F Ambient for Type T Thermocouple Using 10 50 and 60 Hz Filter 0 1 2 3 4 5 6 300 200 100 0 100 200 300 400 10 Hz 50 Hz 60 Hz 0 1 2 3 4 5 6 7 8 9 10 11 600 400 200 0 200 400 600 800 10 Hz 50 Hz...

Страница 98: ...77 F Ambient for Type T Thermocouple Using 250 500 and 1 kHz Filter 0 20 40 60 80 100 300 200 100 0 100 200 300 400 250 Hz 500 Hz 1000Hz 0 20 40 60 80 100 120 140 160 600 400 200 0 200 400 600 800 25...

Страница 99: ...ry A 0 indicates a value of 0 a 1 indicates the decimal value of the position The equivalent decimal value of the binary number is the sum of the position values Positive Decimal Values The far left p...

Страница 100: ...e other positions In the figure below all positions are 1 the value is 32767 32768 1 For example 1111 1000 0010 0011 214 213 212 211 25 21 20 215 16384 8192 4096 2048 32 2 1 32768 30755 32768 2013 1 x...

Страница 101: ...thermodynamic values than were those of the IPTS 68 and EPT 76 Additionally improvements have been made in the non uniqueness and reproducibility of the temperature scale especially in the temperatur...

Страница 102: ...but also has been used successfully in neutral atmospheres or vacuum by Walker et al 25 26 Hendricks and McElroy 41 and Glawe and Szaniszlo 24 The stability of the thermocouple at high temperatures ha...

Страница 103: ...agrees with that of the specified reference table within certain tolerances can be considered to be a type E thermocouple The positive thermoelement EP is the same material as KP The negative thermoel...

Страница 104: ...hermoelement a copper nickel alloy is subject to composition changes under thermal neutron irradiation since the copper is converted to nickel and zinc Neither thermoelement of type E thermocouples is...

Страница 105: ...tions lead to difficulties in obtaining accurate calibrations based on a limited number of calibration points The positive thermoelement is commercially pure 99 5 percent Fe iron usually containing si...

Страница 106: ...converted to nickel and zinc Iron undergoes a magnetic transformation near 769 C and an alpha gamma crystal transformation near 910 C 6 Both of these transformations especially the latter seriously a...

Страница 107: ...5 percent silicon 1 to 2 3 percent aluminum 1 6 to 3 2 percent manganese up to about 0 5 percent cobalt and smaller amounts of other constituents such as iron copper and lead Also type KN thermoeleme...

Страница 108: ...hanges in their chemical compositions due to transmutation are small The KN thermoelements are somewhat less stable than the KP thermoelements in that they experience a small increase in the iron cont...

Страница 109: ...asurements down to 20K Nevertheless types NP and NN thermoelements do have a relatively low thermal conductivity and good resistance to corrosion in moist atmospheres at low temperatures Type N thermo...

Страница 110: ...d the importance of using Inconel sheathing with a very low manganese content to achieve the most stable performance The use of special Ni Cr based alloys for sheathing to improve the chemical and phy...

Страница 111: ...ard 21 describes the purity of commercial type R materials that are used in many industrial thermometry applications and that meet the calibration tolerances described later in this section It does no...

Страница 112: ...ailable platinum that has a nominal purity of 99 99 percent 21 An industrial consensus standard ASTM E1159 87 specifies that rhodium having a nominal purity of 99 98 percent shall be alloyed with plat...

Страница 113: ...material for insulating protecting and mechanically supporting the thermocouple wires Both thermoelements of type S thermocouples are sensitive to impurity contamination In fact type R thermocouples w...

Страница 114: ...M standard 7 for protected type S thermocouples applies to AWG 24 0 51 mm wire This temperature limit applies to thermocouples used in conventional closed end protecting tubes and it is intended only...

Страница 115: ...at the type T thermocouple may be used down to liquid helium temperatures about 4K but that its Seebeck coefficient becomes quite small below 20K Its Seebeck coefficient at 20K is only about 5 6 V K b...

Страница 116: ...sired temperatures ASTM Standard E230 87 in the 1992 Annual Book of ASTM Standards 7 specifies that the initial calibration tolerances for type T commercial thermocouples be 1 C or 0 75 percent whiche...

Страница 117: ...1992 Annual Book of ASTM Standards Vol 14 03 Philadelphia ASTM 1992 102 230 8 Sparks L L Powell R L Hall W J Reference tables for low temperature thermocouples Natl Bur Stand U S Monogr 124 1972 June...

Страница 118: ...P Effect of oxidation on stability of thermocouples Proceedings of the American Society for Testing and Materials Vol 63 1185 1194 1963 19 Bentley R E Short term instabilities in thermocouples contain...

Страница 119: ...H ed Pittsburgh Instrument Society of America 1972 1585 1603 28 Burns G W Strouse G F Mangum B W Croarkin M C Guthrie W F Marcarino P Battuello M Lee H K Kim J C Gam K S Rhee C Chattle M Arai M Sakura...

Страница 120: ...lectrical properties of platinum Engelhard Tech Bull 11 58 71 1969 Also in Temperature Its Measurement and Control in Science and Industry Vol 4 Plumb H H ed Pittsburgh Instrument Society of America 1...

Страница 121: ...nisil thermocouples in production furnaces in the 538 C 1000 F to 1177 C 2150 F range ISA Transactions 18 4 83 99 1979 49 Wang T P Starr C D Oxidation resistance and stability of nicrosil nisil in ai...

Страница 122: ...tley R E The new nicrosil sheathed type N MIMS thermocouple an assessment of the first production batch Mater Australas 18 6 16 18 1986 58 Bentley R E Russell Nicrosil sheathed mineral insulated type...

Страница 123: ...h forming a completely sealed integral junction If the sheath is metal or electrically conductive there is electrical continuity between the junction and sheath The junction is protected from corrosiv...

Страница 124: ...a protective sheath made of electrically insulated material for example ceramic An alternative is to float the metal sheath with respect to any path to chassis ground or to another thermocouple metal...

Страница 125: ...aves thermocouple wires unprotected against corrosive or mechanical damage As shown in the next illustration using an exposed junction thermocouple can result in removal of channel to channel isolatio...

Страница 126: ...iple exposed junction thermocouples do not allow the measuring junctions to make direct contact with electrically conductive process material Preferably use a single exposed junction thermocouple with...

Страница 127: ...Detailed information on the image table is located in Chapter 3 For example to obtain the general status of channel 2 of the module located in slot e use address I e 6 2 Channel 0 Data Word Word 0 Wor...

Страница 128: ...rsion 5 50 or Higher on page E 2 Configuration Using RSLogix 500 Version 5 50 or Higher This example takes you through configuring your 1762 IT4 thermocouple mV input module with RSLogix 500 programmi...

Страница 129: ...en appears While offline double click on the IO Configuration icon under the controller folder and the following IO Configuration screen appears This screen allows you to manually enter expansion modu...

Страница 130: ...gix 500 A communications dialog appears identifying the current communications configuration so that you can verify the target controller If the communication settings are correct click on Read IO Con...

Страница 131: ...are located on a separate tab from channel 3 as shown below To enable a channel click its Enable box so that a check mark appears in it For optimum module performance disable any channel that is not...

Страница 132: ...able Cyclic Calibration Word 4 Bit 0 on page 3 14 for more information Generic Extra Data Configuration This tab redisplays the configuration information entered on the 1762 IT4 configuration screen i...

Страница 133: ...ur channels To properly configure and enable input channel 1 for the setting in the table below add the decimal values given to each of the six parameters These decimal values are listed in the config...

Страница 134: ...Publication 1762 UM002A EN P July 2002 E 8 Module Configuration Using MicroLogix 1200 and RSLogix 500...

Страница 135: ...d update the channel data word CJC Cold junction compensation CJC is the means by which the module compensates for the offset voltage error introduced by the temperature at the junction between a ther...

Страница 136: ...lter A device that passes a signal or range of signals and eliminates all others filter frequency The user selectable frequency for a digital filter full scale The magnitude of input over which normal...

Страница 137: ...ion differential mode rejection A logarithmic measure in dB of a device s ability to reject noise signals between or among circuit signal conductors The measurement does not apply to noise signals bet...

Страница 138: ...valid step response time The time required for the channel data word signal to reach a specified percentage of its expected final value given a full scale step change in the input signal thermocouple...

Страница 139: ...e common mode rejection ratio common mode rejection 3 11 definition G 1 specification A 2 common mode rejection ratio definition G 1 specification A 2 common mode voltage definition G 1 common mode vo...

Страница 140: ...G 2 input filter selection 3 10 input image definition G 2 input module channel configuration 3 4 enable channel 3 6 input module status general status bits 3 2 over range flag bits 3 3 under range fl...

Страница 141: ...ns 4 1 two s complement binary numbers B 1 type B accuracy A 5 A 6 description C 1 effective resolution 3 15 3 16 temperature range 1 1 type C accuracy A 7 A 8 effective resolution 3 17 3 18 temperatu...

Страница 142: ...ion 1762 UM002A EN P July 2002 4 Index U under range flag bits 3 3 update time 3 33 update time See channel update time update time See module update time W wiring 2 1 modules 2 11 routing considerati...

Страница 143: ...AB Parts...

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